1. Technical Field
The present disclosure relates to printing systems, and in particular, to a system and method for printing target colors with process colors utilizing parallel feedfoward neural networks.
2. Description of Related Art
In most multi-color printing systems, multiple color separations are used for marking a substrate, e.g. paper. Each of these color separations mark the substrate with a single colorant, that is, each separation marks the substrate with only one specific colorant, which is different from the colorants of the other color separations. The colorants commonly used are cyan, magenta, yellow and black, also referred to as CMYK. These colorants are commonly referred to as “process colors” because of their wide availability and universal usage. “Colorant” refers, for example, to pigments, dyes, mixtures thereof, such as mixtures of dyes, mixtures of pigments, mixtures of dyes and pigments, and the like. These colorants are also commonly referred to as “inks” or “toners”, and for the purposes of the disclosed subject matter, these terms are to be considered interchangeable. Additionally, the term “printing system” is considered equivalent to and interchangeable with an image forming apparatus, a printer, a printing machine, a copier, a facsimile machine, a multifunction device (e.g., a scanner integrated with a printer), a electrophotography device, a xerography device, an electrophotographic device, a electrostatographic device and/or the like.
As previously mentioned, multi-color printing systems utilize a limited number of color separations for marking a substrate, however, a much wider variety of colors is achievable. Each separation marks the substrate using discrete shapes, such as dots having a circular or oval shape, or periodic line patterns, which in aggregate create a larger set of colors for perception. This concept is generally known as color half-toning, and involves combining two or more patterned separations on the substrate. The selection of color separations and halftone pattern designs are carefully chosen for achieving a desired color.
Although some multi-color printing schemes use CMYK color separations, one technique utilizes a single colorant to precisely print a specific color. These colorants are specially made and are added to the printing system as a fifth color, or as a single color in specially made printing systems. More precise colorants are usually referred to as “spot colors” because they are applied on a particular spot of the substrate. One system of categorizing spot colors is referred to as the “pantone color” color system. These spot colors are used to precisely display colors such as in logos, trademarks, service marks, and brands, because it is desirable for a company or institution to have the public at large (and especially customers) to readily recognize these types of reproduced items. Target colors are defined herein as a color desired by a user, machine, process, software, a printing system technician, a graphics artist, and the like, for printing with sufficient precision of expected human perception; in other words, a “target color” is some color that has to be obtained with sufficient precision, such as by using CMYK colors or with the addition of some specially-bended toner or ink e.g., CMYK+.
Pantone colors and spot colors may be a target color of a printing system. Target colors may be obtained using the CMK color separations, using specially blended toners or inks, or using printing systems having more than four color separations, e.g., CMYK+ systems. Accurate and repeatable colors facilitate easy recognition of these reproduced items slowly, over time, and after several repeated exposures, making these items easily recognizable by the public at large.
Most printer manufactures make special inks for spot color printing, however, there is customer demand for using the process color for spot color printing as well. Using CMYK color separations to make “spot colors” requires color printing accuracy. Additionally, the color accuracy should be uniform across multiple print engines although there may be slight manufacturing differences between print engines of different models or between print engines of the same printer models.